Sleepers are the rags-to-riches late-round stories who give far more than expected. After taking a stab at who we think might emerge from the shadows in the American League, we turn our attention to the best potential sleepers in the Senior Circuit, highlighted team-by-team around the league (in predicted order of finish):
Brown is a favorite pick for NL Rookie of the Year as a five-tool, five-category star in the making. He has a great supporting cast and home hitter's park to spend half his games in, too. The right-field spot is vacant thanks to the departure of Jayson Werth, so Brown could be a .280-20-80-20 producer.
Honorable mention: Placido Polanco is coming off an injury-plagued year, but the veteran tends to be plenty productive as someone just off the fantasy radar as a late-round pick or waiver claim. He could slap his way to a consistent average and should be a solid position-filler if he can get through the season healthy coming off elbow surgery.
The Braves are a gold mine for sleepers this spring, mostly because they have a slew of NL Rookie of the Year contenders in Kimbrel, if he closes, first baseman Freddie Freeman and lefty No. 5 starter Mike Minor. Brandon Beachy is competing for a rotation spot, too. Any one of those could challenge Brown for NL ROY honors.
Honorable mention: Outside of the rookies, who tend to be more overhyped than undervalued, let's bring Nate McLouth back into the discussion. He was a mess last year after some productive years in Pittsburgh. Perhaps he can get back to being a 20-20 candidate.
Sanchez is one of those sophomores who will be overlooked this spring. He wasn't quite considered at elite prospects -- especially not at the deep first-base position -- but he had a strong rookie season in the majors. If he can improve on 2010, you could get a .290-30-100 guy in the depths of this position.
Honorable mention: Chris Coghlan went from NL ROY to fantasy bust a year ago, but you shouldn't completely lose sight of him as being capable of winning a batting title. He is a Michael Young-like hit machine that could develop into a perennial candidate for 200 hits, even if the power isn't really there in a pitcher's park.
The Mets are hoping to catch lightning in a bottle with Young coming off shoulder woes. You should hate pitchers with shoulder issues, but if R.A. Dickey can prove to be fantasy viable as a knuckleballer in that cavernous park, perhaps Young can enjoy a renaissance, too.
Honorable mention: Jon Niese quietly had a solid rookie season for the woebegone Mets. He could be a solid No. 2 starter behind Mike Pelfrey until Johan Santana (shoulder) is ready in June.
Everyone will ignore then Nationals until Stephen Strasburg (Tommy John elbow surgery) returns in 2012, but don't sleep on Zimmermann. He has power stuff coming off his own UCL replacement surgery and is ready for his first full season in the majors. He could be a candidate to post a sub-3.00 ERA and a strikeout per inning as a late-rounder.
Honorable mention: Drew Storen has been called the Nats closer of the future since he was drafted, and that future should be now. Tyler Clippard and Sean Burnett are options to close as well, but neither has the high ceiling Storen does for the Nats and fantasy owners.
Few know how good Marcum is. He was stuck north of the border pitching for an also-ran with the Blue Jays in the AL Beast last year. He now gets a contender with a potent offense. We should find just how good this Tommy John survivor can be this season. Oh, and he is arbitration eligible next winter and a potential free agent in 2013.
Honorable mention: Most will be expecting John Axford to duplicate his surprising rookie season as a full-time closer for the first time. Well, Zach Braddock could have something to say about it. He is the power-armed prospect who had the closer-in-waiting label before Axford came out and surprised everyone. Braddock could steal Axford's thunder by midseason.
Unless you're an intense fantasy player who studies the depths of the minor leagues or prospects, you probably don't see much out of Freese. He epitomizes the unknown and unseen, due to injury and underperformance. You should know Freese is capable of being a .280-25-90 guy.
Honorable mention: Lance Berkman is one of the few old players on this list. We have seen plenty from him, but many saw enough last season to believe he is washed up. He could be rejuvenated Vladdy Guerrero-like with Albert Pujols, Matt Holliday and the Cardinals.
This is what injury-risk sleepers are all about. Volquez was a Cy Young candidate before Tommy John surgery. Last season, he could hardly hold down a rotation spot down the stretch, much less a spot on fantasy teams. He should be widely underrated this spring.
Honorable mention: Mike Leake didn't do anything particularly impressive after the All-Star break, going 2-3 with a 6.91 ERA after looking like an NL ROY candidate in the first half: 6-1, 3.53. Leake was making the jump straight from college to the majors, though. He may closer to his first-half form in his first true full season in the bigs (he was shut down after going 1-2, 8.83 in August, as should be expected from a first-time pro that has never been stretched out past June).
Dewitt has more pop in his bat than he has shown, and he could be a 15-homer fantasy second baseman this season. He only slugged at that rate in August, but he did enough to enter the season as the Cubs' everyday option at the spot. He will be more of an NL-only sleeper than a mixed-league one.
Honorable mention: Andrew Cashner could be stuck in the Pitch-22, the Catch-22 for pitchers: Good enough to start, but too valuable in relief. But the Cubs look like they have depth in their bullpen now with Carlos Marmol closing and Kerry Wood setting up. Cashner could be stretched out to start and could prove to be a front-line guy with that power arm.
Everyone will agree Wallace has a stick that could produce big numbers, but the Cardinals, A's and Blue Jays have already moved him out of their systems. Wallace has been traded for some serious players, though. He could be a poor man's Berkman in replacing that Houston favorite.
Honorable mention: Bud Norris is more highly regarded on draft boards than Wallace, but he is more certain to make an impact this season as a third-year starting pitcher. He could strike out more than 220 batters if he reaches 200 innings for the first time.
Joel Hanrahan might open the season as the Pirates' closer, but Meek is more certain to finish as it. Meek is younger and has knockout stuff fitting for a closer of the future. Frankly, he should be the closer of the present.
Honorable mention: Everyone loves Andrew McCutchen, Pedro Alvarez, Jose Tabata and Neil Walker. No one likes Ryan Doumit anymore. Doumit might not start, but he can hit enough and play enough to be a valuable pick at the thin catcher position, at which he still qualifies.
If you can cover paper over Stewart's big-league numbers and just remember the hype as a prospect, you can envision what this writer does: a .290-30-100 breakthrough.
Honorable mention: Chris Iannetta was terrible for fantasy owners last year, mostly because veteran Miguel Olivo stole his thunder and his starting job in the first half. Well, Olivo is now in Seattle and Iannetta is back where he was a few years ago, down the list of potential 20-homer catchers. Iannetta can put it all together as a first-time, full-time catcher at age 27.
Kung Fu Panda came out swinging in '09 only to go bust as an early-round pick last season. You should figure he gets back to being his pre-'10 form in the power categories. It should make him a nice option after the elite corner infielders are off the board. He is coming at a bargain rate this spring.
Honorable mention: The Giants are more likely to be overrated due to their postseason heroics than underrated, but like Sandoval, Mark DeRosa is coming off a year far below expectations. It makes him an affordable NL-only sleeper and maybe even a mixed-league option if he serves a super utilityman role again, playing around the infield and outfield.
Loney is one of those former top prospects who has looked like he could go .300-20-100 in spurts but has never put it together. Well, guess how old he turns this season? Yep, 27. This could be the year and he will be viewed as a mere .290-15-90-10 player. The good news? Those are baseline numbers in what should be his best season yet.
Honorable mention: Ted Lilly always tends to be overlooked on draft day. This year should be no different. If Loney, Matt Kemp and Andre Ethier finally put big years all together, Lilly could sneak up and be a valuable 15-plus-game winner.
With Adrian Gonzalez in Boston, the Padres are a team of potential sleepers one through eight in the batting order. With that said, let's highlight the home-grown product that has been around the longest and is still just 26 -- 27 in May. He could be the top offensive threat in this lineup this season.
Honorable mention: Kyle Blanks was supposed to be a massive slugger last season; now he is coming off an injury-plagued year and not being counted on to start. He is still a behemoth that could surprise with a 25-plus homer season once he proves healthy and capable of playing regularly, though.
Montero, like Iannetta above, has shown flashes of 20-homer potential as a catcher. He is coming off an injury-plagued year and is finally slated to be uncontested at the position now that Chris Snyder is in Pittsburgh. Montero is going to go well after the top catchers but he could rebound an perform like one of them.
Honorable mention: Brandon Allen is the D'backs' version of Blanks: A behemoth slugger with 30-homer potential who hasn't made good on his promise. Allen will get a chance to start out of Spring Training and could prove useful as a streaky slugger in spurts.
Eric Mack writes bi-weekly for SI.com. You can mock him, rip him and (doubtful) praise him before asking him for fantasy advice on Twitter @EricMackFantasy. Hit him up. He honestly has nothing better to do with his free time.